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KlementineJBS / USYD_PhD_ELN

This repository forms the electronic laboratory notebook (ELN)for Klementine Burrell-Sander's PhD's
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KBS29-7 - Bromination of KBS28 with phosphorus tribromide #162

Closed KlementineJBS closed 6 months ago

KlementineJBS commented 7 months ago

Link to HIRAC

KBS29 Phosphorus tribromide reaction OH to Br.docx

Previous attempt is #156

Reaction scheme

KBS29 - Phosporus tribromide reaction

Outcome

584.4 mg, 2.03 mmol, 23%

KlementineJBS commented 6 months ago

5.12.23

SM = 1.9567 g (8.69 mmol)

  1. Added SM to a vial with 24 mL DCM.
  2. Added phosphorus tribromide (1 mL)
  3. Reacted for ~1 hr at rt

TLC indicated presence of an unknown spot. Couldn't figure out whether it was being formed more as reaction progressed or not so turned reaction off, took a quick NMR and worked up.

Added 20 mL NaHCO3, which caused reaction to form what looked like 3 layers:

Worked up with DCM (3 x 50 mL), washed with brine (25 mL).

Vial: 15.7762 Mass: 1.9510 g (6.77 mmol if pure)

KlementineJBS commented 6 months ago

H NMR

Interestingly, reaction mixture aliquot seems to contain less of the SM than the crude reaction mixture after it was worked up. Unsure why this is.

KBS29-7 cr.pdf KBS29-7 cr_1.zip KBS29-7 RM_1.zip

KlementineJBS commented 6 months ago

Column

Columned about 280 mg of material with the hope of obtaining a pure solid to use in recryst screenings. F10-21 is pure sample but in relatively low yield (roughly 50% by mass) and remained stubbornly as an oily brown liquid rather than turning to a crystalline golden solid as seen in #156

KBS29-7 F1-9_1.zip KBS29-7 F10-21_1.zip KBS29-7 F24-29_1.zip KBS29-7 column.pdf

F10-21

Vial: 15.7956 Mass: 107 mg (0.373 mmol)

KlementineJBS commented 6 months ago

Columns 2 and 3

Decided to just column the whole lot. First column was ethyl acetate and hexanes and no product was recovered, only azide (column b, F1-13). Second column was methanol/DCM.

Column c, F1-24

vial: 15.8237 mass: 584.4 mg, 2.03 mmol, 23%

Column c, F25-34

vial: 15.5357 mass: 296.8 mg

KlementineJBS commented 6 months ago

H NMR

NMR confirms that column b F1-13 contains azide, column c F1-24 contains product, and column c F25-34 contains a mixture of product and SM.

KBS29-7 column b and c fractions.pdf KBS29-7b F1-13_1.zip KBS29-7c F1-24_1.zip KBS29-7c F25-34_1.zip

KlementineJBS commented 6 months ago

Fractions 25-34 will be combined with any remaining unpurified material and purified in a job lot.